A human that eats of the Minotaur is a cannibal.

Pros

Cons

The Minotaur's mother was a human. Though the Minotaur was not 100% human, he was OF humans and was, himself, a part of the larger human family tree. This being the case, it would be cannibalism, as a human would be eating some human in eating the Minotaur.

Being half human, it is likely to cause the negative effects of cannibalism (prions) so while debatable if it is ethically cannibalism, it is probably practical cannibalism.

Cannibalism as a human act is fundamentally different from zoological cannibalism, being complicated as it is by Imperialist misconceptions of the wider world. Without an accepted, common definition for human cannibalism, it could not be called cannibalism with any force.

The Minotaur is not human and therefore the act would not be cannibalism.

If a human eats a human body part of the Minotaur, he is a cannibal. If he eats a bovine part of it, he isn't.